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(No Model.)

G. w. BROWN.

AUTOMATIC FIRE ALARM SYSTEM.

N0; 506,'582.' Patented Oct, 10, 1893.

N T El RI I'NVE 2 sham-sheet 1.

(No Model.)

2 Sheets-Sheet 2. G .W. BROWN. AUTOMATIC FIRE ALARM SYSTEM.

Patented Oct. 10, 1893.

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\A/ITNEEEES:

UNITED STATES PATENT OFFICE.

GILMAN \V. BROWN, OF WVEST N EWBURY, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TO HAYDN BROWN, OF SAME PLACE.

AUTOMATIC FIRE-ALARM SYSTEM.

SPECIFICATION forming part of Letters Patent No. 506,582, dated October 10, 1893. v

To aZZ whom it may concern:

Be it known that I, GILMAN W. BROWN, of West Newbury, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Automatic Fire-Alarm Systems, of which the following is a specification.

This invention relates to a system for transmitting signals, and is especially designed and'adapted to be used as an automatic fire alarm system.

My present invention has for its object, to provide aconstruction and arrangement of apapratus whereby an annunciator drop preferably of a construction as will be described, may have its magnet coils included in a normally closed branch circuit connected to the main line circuit, in which are located thermostats substantially of the construction shown and described in United States Patent- N 0. 463,608, granted to me November 17, 1891, the branch circuit containing the annunciator drop magnets being without current, while the thermostats remain inactive,but which is adapted to be brought into circuit with the main line battery upon the operation of a thermostat as will be described. The annunciator drop referred to is preferably composed of a pivoted target operated in one direction by a pivoted armature movable between the coils to the electro magnet, the said target being provided with an indication preferably the word fire which isv normally concealed from view, but which is adapted to be brought into view when the electro-magnet is energized by the operation of a thermostat.

The particular features in which my invention consists, will be pointed outin the claims at the end of this specification.

Figure 1 is a frontelevation of an annunciator, provided as herein shown with four annunciator drops having their magnets connected to an electric circuit extended through or over four sections or floors of a building or other structure to be protected. Fig. 2 is a front elevation of one of the annunciator drops shown in Fig. 1; Fig.3 a top or plan ing the annunciator shown in Fig. 1, as connected in circuit with suitable thermostats, located on the different floors of the building or other structure; Fig. 6 a top or plan view of the form of the thermostats preferred by me; Fig. 7,a longitudinal section of the thermostat shown in Fig. 6 on theline 7 7; Fig. 8 an under side view in perspective of the thermostat shown in Fig. 6 with the bottom plate or cover removed, and Figs. 9 and 10 diagrams or circuits to enable the operation of the annunciator to be more readily comprehended.

Referring to Fig. 1, A represents an annunciator case or frame, provided with a door A having as represented, suitable holes or openings a, there being four such holes herein shown, with which register targets a of annunciator dropsA there being four such annunciator drops herein shown, which are located within the case A. Each annunciator drop A may and preferably will be made substantially as shown in Figs. 2 and 3, it consisting of an electro-magnet having two coils a a connected by a yoke 0. and front strap' a between which is pivoted a shaft or arbor a having secured to or forming part of it an armature a located between the pole pieces a a of the electro magnets 01. 01. The pole pieces a a have mounted on them magnetic heads 2 3, preferably circular in shape and which are herein shown as separated from the coils of the magnets by insulating washers 4 5, the said magnetic heads extending the fieldof force of the pole pieces a a and co-operating with the armature a mounted to swing or oscillate in a line parallel with the magnetic heads. The target a is loosely mounted on a screw or stud b, and is adapted to be turned on the stud b as a pivot by an arm or projection b on the armature a the target a normally occupying a substantially vertical position, in which it is maintained by a pin 6 on the front strip a engaging a finger b on the said target.

In practice, the annunciator case A, containing as many annunciator drops as there are floors or sections of the building or other structure to be protected, may and preferably will be located near the main entrance of the building, and the electro magnets or a of shown in Fig. 9.

each annunciator drop are connected to one line wire of a main line circuit extended through the building.

Referring to Fig. 5, I have represented in diagram four floors of a building marked respectively, '1, 2, 3, and t, and have extended through the said building, an electric circuit consisting of the positive wire b and the negative wire Z1 of a battery b.

The line wires b Z2 on each floor have included in them, a series of thermostatic instruments B, shown separately in Figs. 6 to 8 inclusive, they being preferably made as shown in said figures.

Referring to Figs. 6 to 8 inclusive represents a porcelain or other insulating base preferably made concaved on its upperside and provided with a detachable bottom 0' of nsulating material, which is secured to the base 0 by suitable screw rod-s 0 The base 0 has secured to its under side two sets of circuit terminals, consisting of metallic springs a c and metallic strips or contact plates 0 c, the said strips being secured to the insulating base 0 at one end by suitable nuts 0 on the threaded rod 0 and the metallic springs c 0 being also firmly secured to the base cby like nuts 0 normally secured to the metallic strips 0 c by soft solder or other fusible connections, and the said springs on their under sides have secured to or forming part of them, hook shaped arms 0 0 which project through suitable slots 0 0 in the base a, and are adapted to be 'brought in contact with pole'changing circuit terminal strips 0 0 secured respectively to the metallic plates 0 c.

In the operation of the thermostats, eifected by a rise in temperature, as by the breaking out of a fire, the fusible connection joining the springs a c to the contact plates 0 c become melted or ruptured, and permit the said springs to separate from the said plates and bring the hooked arms 0 c into contact with the terminal strips 0 0, thereby reversing the current through the electric circuit, substantially as described in the patent referred to. The electro-magnet a a of each annunciator drop is connected by branch Wires d d to one of the line wires of the metallic circuit, the said branch wires being connected as herein shown, to the positive wire. The electro magnets a a of each annunciator drop are located in a normally closed branch through which no current flows so long as the thermostats in the main line are in their normal condition and ready for operation as When this normal condition prevails no current will flow through the magnets of the annunciator drop, because there is no difierence of potential between the points at which the branches which include said electro magnets are connected with the main line. It will be seen therefore that the effect of reversing the current by the release of the springs of any thermostat which The metallic springs c c areis in the mainline between the terminals of any annunciator magnet, in effect transfers one terminal of the annunciator magnet from one side of the line to the other, or in other words causes a difierence of potential between the two terminalsof the circuit through the annunciatormagnets,causingthecurrenttofiow. To illustrate, let it be supposed that the springs c c of one of the thermostats lS operated by the breaking out of a fire. In this case as above described, the magnets c c of the annunciator drop are included in circuit with the battery 12 which circuit may be traced in Fig. 10 as follows, viz: from the positive pole of the battery 19 by wire b to the terminal plate 0 thence by the branch wire (1 through the magnets c 0 and wire d, back to the portion of the wire b connected to the spring 0 thence by the forked arm 0 and terminal strip 0 to the terminal plate 0 thence by the wire Z1 back to the battery. As soon as the magnets c c are energized as described, the armature a for the annunciator magnets connected in circuit with the particular floor upon which the fire has broken out, is attracted by its magnets a a and moved in the direction indicated by the arrows in Fig. 2, thereby causing the pin 1) to throw the target a over, so as to bring the word fire in front of the opening a, corresponding to the particular floor upon WlllCll the thermostat has operated.

The thermostatic system may and preferably will include a signal receiving apparatus, represented as a bell D, which may be operated substantially as described in the patent referred to, but which preferably will be constructed substantially as described in an application, Serial No. 444,729,. filed concurrently herewith.

As represented in the drawings, the receiving instrument, is disconnected from the main lines b 19 but may be connected thereto by the switches (1 It will be noticed that the electro-magnets of the annunciator drop are in a normally closed branch circuit, which in practice is controlled by the thermostat and which normally is free from current. This arrangement of the annunciator magnets, possesses advantages over other arrangementsnow commonly employed, in which the annunciator magnets are located in a closed circuit contain-- ing a battery, and also in which the annunciator magnets are located in an open circuit. When the annunciator magnets are located in the closed circuit containing a battery, the latter is gradually being used up and requires attention and care, and in the case of the open circuit, a contact must be made to energize the annunciator magnets, which contact'is liable to become inoperative, and in an automatic fire alarm system, it is very essential that all parts should be positive and reliable, in their operation.

The magnets of the annunciator dropsshould be made ofcomparatively high resistance, so that they will divert only a small proportion of the current of the main battery.

- I do not limit myself to the use of the described improvements for fire alarm purposes, so far as the general system is concerned. 'The system may be used as a-burglar alarm by substituting for the pole changing thermostats any other suitable pole changing or current reversing devices, such as switches which may be operated by the opening of doors or windows or otherwise.

I claim- 1. An alarm or signaling system consisting of the following instrumentalities, viz: anormally closed main line circuit, a normally.

closed branch circuit normally connected to one side of the main line circuit, an annunciator magnet included in said branch circuit, and a current reversing or pole changing de- Vice in the main line circuit constructed, when operated, to reverse the current through the main line and to connect the said branch circuit'with the other side of the main line circuit, thereby causing the current to flow through the annunciator magnet, substantially as described.

2.1 An automatic fire-alarm system consist ing of the following instrumentalitiesviz: a normally closedmain line circuit, a normally closed branch circuit connected to the main line circuit, as described, to obtain uniform potential in said branch circuit, an annunciator magnet insaid branch circuit normally inoperative while the potential at the ends of the branch circuit remains unchanged, anda.

pole-changing thermostat in the main line operated by a rise in temperature to effect a change in potential in the'branch circuit and energize the said annunciator magnet, substantially as described. 1

In an automatic fire alarm system, the combination with a main line provided with a normally closed thermostat consisting of spring members 0 0 having projections or arms '0 0 terminal plates 0 c to which the spring members are normally connected by fusible connections, and pole changing strips 0 0 with which the projections 0 0 00-0 erate when thethermostat is operated, of an annunciator magnet having its coils included in a-normally closed branch circuit 01 d, one

a a target a, pivoted to the front strap, an

armature a pivoted between the coils of the said electromagnets, a stud or pin 1) on the armature a to act on the target a, substantially as described.

5. An alarm'and signaling system, consisting of the following instrumentalities, viz:a.

normally closed main line circuit; a polarized electro magnet therein; a normally closed branch circuit normally connected to one side of the main line circuit; an annunciator-magnet included in said branch circuit; and a.

current-reversing or pole-changing device in the main line circuit, constructed, when operated, to reverse the current through the main line and operate the polarized electromagnet, and to connect the said branch circuit with the other side of the main linecircuit to operate the annunciator-magnet; substantially as described.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 9th day of August, A. D. 1892.

GILMAN W. BROWN.

Witnesses: 1 d

O. F. BROWN, I N. S. MCLEOD. 

